title: Effects of passive smoking on snoring in preschool children.
abstract: OBJECTIVE
  To examine the association between passive smoking and snoring in preschool children using parent-reported questionnaires and urine cotinine levels.
  
  
  METHODS
  This was a population-based cross-sectional survey of 2954 children aged 2-6 years in Hong Kong. Parent-reported questionnaires provided information on snoring and household smoking. One-third of children randomly chosen from the cohort provided urine samples for cotinine analysis. Increased urine cotinine was defined as urinary cotinine concentration ≥ 30 ng/mg creatinine. Using multivariate logistic regression analysis, we analyzed the association between snoring and passive smoking, controlling for potential confounders including age, sex, body mass index z-score, atopic diseases, recent upper respiratory tract infection, parental allergy, parental education, family income, and bedroom-sharing.
  
  
  RESULTS
  A total of 2187 completed questionnaires were included in the final analysis, and 724 children provided urine samples for cotinine measurement. After adjustment for confounding factors, questionnaire-based household smoking (>10 cigarettes/d: OR = 2.22, 95% CI = 1.02-4.81) and increased urine cotinine (OR = 4.37, 95% CI = 1.13-16.95) were significant risk factors for habitual snoring (snoring ≥ 3 nights per week). For occasional snoring (snoring 1-2 nights per week), reported household smoking (1-10 cigarettes/d: OR = 1.41, 95% CI = 1.14-1.76; >10 cigarettes/d: OR = 1.56, 95% CI = 1.05-2.31), and increased urine cotinine (OR = 1.82, 95% CI = 1.03-3.20) were also identified as significant risk factors. A dose-effect relationship was found for snoring frequency and adjusted natural logarithms of urinary cotinine concentrations (P < .001).
  
  
  CONCLUSIONS
  Environmental tobacco smoke exposure is an independent risk factor for snoring in preschool children. Parents' smoking cessation should be encouraged in management of childhood snoring.
authors.affiliation: Department of Pediatrics, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong. Electronic address: jodiezy@163.com.
authors.forename: Yin
authors.initials: Y
authors.lastname: Zhu
authors.forename: Chun Ting
authors.initials: CT
authors.lastname: Au
authors.forename: Ting Fan
authors.initials: TF
authors.lastname: Leung
authors.forename: Yun Kwok
authors.initials: YK
authors.lastname: Wing
authors.forename: Christopher Wai Kei
authors.initials: CW
authors.lastname: Lam
authors.forename: Albert Martin
authors.initials: AM
authors.lastname: Li
mesh_terms: D000886:Anthropometry / Q000379:methods; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D003367:Cotinine / Q000652:urine*; D003430:Cross-Sectional Studies; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006723:Hong Kong; D006801:Humans; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D010290:Parents; D012307:Risk Factors; D012913:Snoring / Q000139:chemically induced*; D011795:Surveys and Questionnaires; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D014028:Tobacco Smoke Pollution; D003367:Cotinine
keywords: BMI; Body mass index; SDB; Sleep-disordered breathing